Logical partitioning in redundant systems

ABSTRACT

Provided are a method, system, and article of manufacture, wherein a plurality of processing nodes in a storage system are partitioned into a plurality of logical processing units, and wherein the plurality of logical processing units can respond to I/O requests from a host coupled to the storage system. At least two logical processing units are grouped, wherein data in a first storage coupled to a first logical processing unit of the least two logical processing units is mirrored by data in a second storage coupled to the second logical processing unit of the at least two logical processing units. In response to a failure of the first logical processing unit, an I/O request from the host is responded to via the second logical processing unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Application Ser. No. 10/675,323filed on Sep. 29, 2003, which is incorporated herein by reference in itsentirety.

BACKGROUND

1. Field

The present disclosure relates to a method, system, and an article ofmanufacture for logical partitioning in redundant systems.

2. Description of Related Art

Redundant information technology systems, including storage systems, maystore the same data in multiple nodes, where a node may be acomputational unit, a storage unit, etc. When one node of a redundantsystem is unavailable, an alternate node of the redundant system may beused to substitute the unavailable node.

An enterprise storage server (ESS), such as the IBM* TotalStorageEnterprise Storage Server*, maybe a disk storage server that includesone or more processors coupled to storage devices, including highcapacity scalable storage devices, Redundant Array of Independent Disks(RAID), etc. The ESS may be connected to a network and include featuresfor copying data in storage systems. An ESS that includes a plurality ofnodes, where a node may have a plurality of processors, may be used as aredundant information technology system.*IBM, IBM TotalStorage Enterprise Storage Server, Enterprise SystemConnection (ESCON), OS/390 are trademarks of International BusinessMachines Corp.

In ESS units that have a plurality of nodes, a pair of nodes may provideredundancy. For example, one node may be referred to as a primary nodeand another node may be referred to as a secondary node. If the primarynode fails, the secondary node takes over and performs the functions ofthe primary node.

In many redundant systems that use a primary node and a secondary nodeto provide redundancy, entire nodes may fail. However, the failure of anentire node, especially in situations where the failed node includesmultiple central processing units (CPUs), can cause system performanceto degrade.

SUMMARY

Provided are a method, system, and article of manufacture, wherein aplurality of processing nodes in a storage system are partitioned into aplurality of logical processing units, and wherein the plurality oflogical processing units can respond to I/O requests from a host coupledto the storage system. At least two logical processing units aregrouped, wherein data in a first storage coupled to a first logicalprocessing unit of the least two logical processing units is mirrored bydata in a second storage coupled to the second logical processing unitof the at least two logical processing units. In response to a failureof the first logical processing unit, an IFO request from the host isresponded to via the second logical processing unit.

In further embodiments, the storage system has at least two processingnodes, wherein the plurality of logical processing units are distributedacross the at least two processing nodes, wherein one processing nodeincludes a plurality of central processing units, and wherein in theevent of the failure of the first logical processing unit, the pluralityof processing nodes stay operational.

In additional embodiments, an administrative console is coupled to theplurality of processing nodes of the storage system. Information onprocessing requirements, memory requirements and host bus adapterrequirements for the plurality of logical processing units are processedat the administrative console prior to partitioning,

In yet additional embodiments, one or more partitioning applications arecoupled to the plurality of logical processing units. In response togrouping the at least two logical processing units, initial program loadof the first logical processing unit is started. The one or morepartitioning applications determine an identification of the secondlogical processing unit grouped with the first logical processed unit.The one or more partitioning applications present common resources tothe first and second logical processing units.

In further embodiments, a request for memory access of a logicalprocessing unit is received from the first logical processing unit. Oneor more partitioning applications coupled to the plurality of logicalprocessing units determine whether the logical processing unit isgrouped with the first logical processing unit. If the logicalprocessing unit is grouped with the first logical processing unit, thenthe memory access of the logical processing unit is allowed to the firstlogical processing unit. If the logical processing unit is not groupedwith the first logical processing unit, then the memory access of thelogical processing unit is prevented to the first logical processingunit.

In still further embodiments, a write request is received from the hostto the plurality of processing nodes in the storage system. One or morepartitioning applications write data corresponding to the write requestto the first storage coupled to the first logical processing unit andthe second storage coupled to the second logical processing unit.

In yet additional implementations, a read request is received from thehost to the plurality of processing nodes in the storage system. One ormore partitioning applications read data corresponding to the readrequest from the first storage coupled to the first logical processingunit.

In further implementations, the partitioning and grouping are performedby one or more partitioning applications coupled to the plurality ofprocessing nodes, wherein the one or more partitioning applicationscomprise a hypervisor application of a redundant system.

The implementations create a plurality of logical processing units froma plurality of processing nodes in a storage system. A pair of logicalprocessing units form a redundant system, where if logical processingunit is unavailable, the other logical processing unit may be used tosubstitute the unavailable logical processing unit. In certainembodiments, in the event of a failure of a logical processing unit, theprocessing node that includes the failed logical processing unitcontinues to operate.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 illustrates a block diagram of a computing environment, inaccordance with certain described aspects of the invention;

FIG. 2 illustrates a block diagram of partner virtual machines, inaccordance with certain described implementations of the invention;

FIG. 3 illustrates logic for implementing partner virtual machines, inaccordance with certain described implementations of the invention;

FIG. 4 illustrates logic for initial program load of partner virtualmachines, in accordance with certain described implementations of theinvention;

FIG. 5 illustrates logic for providing security for memory access inpartner virtual machines, in accordance with certain describedimplementations of the invention;

FIG. 6 illustrates logic for providing security for reinitializingpartner virtual machines, in accordance with certain describedimplementations of the invention;

FIG. 7 illustrates logic for processing reads, writes, and failures inpartner virtual machines, in accordance with certain describedimplementations of the invention; and

FIG. 8 illustrates a block diagram of a computer architecture in whichcertain described aspects of the invention are implemented.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings which form a part hereof and which illustrate severalimplementations. It is understood that other implementations may beutilized and structural and operational changes may be made withoutdeparting from the scope of the present implementations.

FIG. 1 illustrates a block diagram of a computing environment, inaccordance with certain described aspects of the invention. A storagesystem, such as an ESS unit 100 is coupled to at least one host 102 viaone more host bus adapters 104 a . . . 104 m. The ESS unit 100 is alsocoupled to an administrative console 106.

The ESS unit 100 may include two nodes 108, 110, where a node maybe aprocessing node, such as, a computational unit. A node may have one ormore central CPUs and may be partitioned into one or more logicalprocessing units, such as, virtual machines, by a partitioningapplication. For example, the node 108 may have one or more CPUs 112,and the node 108 may be partitioned into the virtual machines 114 a . .. 114 n by a partitioning application 116. Similarly, the node 110 mayhave one or more CPUs 118, and the node 110 may be partitioned intovirtual machines 120 a . . . 120 n by a partitioning application 122. Avirtual machine, such as virtual machines 114 a . . . 114 n, 120 a . . .120 n, may appear as computational unit to the host 102.

While the ESS unit 100 is shown as including two nodes 108 and 110, inalternative embodiments the ESS unit 100 may include a fewer or a largernumber of nodes. For example, in certain embodiments the ESS unit 100may comprise of only one node partitioned into a plurality of virtualmachines, and in certain embodiments the ESS unit 100 may comprise ofthree nodes where the nodes may be partitioned into one or more virtualmachines. In alternative embodiments, instead of the ESS unit 100, othercomputational or storage systems may be used, where the othercomputational or storage systems are partitioned into a plurality ofvirtual machines.

In certain embodiments, the host 102, and the nodes 108, 110 may be adevice such as a personal computer, a workstation, a server, amainframe, a hand held computer, a palm top computer, a telephonydevice, network appliance, etc. The host 102 may include any operatingsystem (not shown), such as the IBM OS/390* operating system. The host102 may also include at least one host application 124 that sendsInput/Output (I/O) requests to the ESS unit 100.

The host bus adapters 104 a . . . 104 m operate over Enterprise SystemConnection (ESCON)* channels or any other data interface mechanism(e.g., fibre channel, Storage Area Network (SAN) interconnections, etc.)and may allow communication between the host 102 and the plurality ofvirtual machines 114 a . . . 114 n, 120 a . . . 120 n. For example, incertain embodiments, the host bus adapter 104 a may allow the host 102to communicate with the virtual machines 114 a, 120 a, and the host busadapter 104 b may allow the host 102 to communicate with the virtualmachines 114 b, 120 b.

The administrative console 106, may be a device, such as a personalcomputer, a workstation, a server, a mainframe, a hand held computer, apalm top computer, a telephony device, network appliance, etc., that isused to administer the ESS unit 100. In certain embodiments, theadministrative console 106 may include an administrative application 126that is used to configure the ESS unit 100.

Therefore, FIG. 1 illustrates a computing environment where the hostapplication 124 sends I/O requests to the ESS unit 100. The ESS unit 100maintains a redundant system to satisfy the I/O requests by grouping thevirtual machines into pairs, i.e., partners. If one virtual machine of apair is unavailable to satisfy the I/O requests, then the other virtualmachine of the pair can satisfy the I/O requests.

FIG. 2 illustrates a block diagram of partner virtual machines 200 a . .. 200 n, in accordance with certain described implementations of theinvention. Partner virtual machines, such as, partner virtual machines200 a, may include two virtual machines. For example, in certainembodiments partner virtual machines 200 a include virtual machines 114a and 120 a, partner virtual machines 200 b include virtual machines 114b and 120 b, and partner virtual machines 200 n include virtual machines114 n and 120 n. Therefore, partner virtual machines may include avirtual machine from node 108 and another virtual machine from node 110.

Partner virtual machines are comprised of two virtual machines, where avirtual machine may be referred to as a partner of the other virtualmachine. For example, partner virtual machines 200 b are comprised ofvirtual machines 114 b and 120 b. Therefore, virtual machine 114 b is apartner virtual machine of virtual machine 120 b and vice versa.

Data in a first storage coupled to a first virtual machine of partnervirtual machines is mirrored by data in a second storage coupled to asecond virtual machine of the partner virtual machines. For example,data in storage of virtual machine 114 a may be mirrored by data instorage of virtual machine 120 a. The first virtual machine may bereferred to as a primary virtual machine and the second virtual machinemay be referred to as a secondary virtual machine. The virtual machinescan respond to I/O requests from the host 102, sent by the hostapplication 124 via the host bus adapters 104 a . . . 104 m to the ESSunit 100.

Therefore, FIG. 2 illustrates how partner virtual machines 200 a . . .200 n are set up within the ESS unit 100. The partner virtual machinescreate a redundant system, wherein if one virtual machine fails theother virtual machine included in the partner machines can substitutethe failed virtual machine.

FIG. 3 illustrates logic for implementing the partner virtual machines200 a . . . 200 n, in accordance with certain described implementationsof the invention. The logic of FIG. 3 is implemented by theadministrative application 126 and the one or more partitioningapplications 116, 122. In certain alternative embodiments, thepartitioning applications 116, 122 or elements of the partitioningapplications 116, 122 may also reside in the host bus adapters 104 a . .. 104 m. Although, the embodiments illustrate two partitioningapplication 116, 122 there may be fewer or more partitioningapplications. Additionally, the two partitioning applications 116 and122 may be combined or referred to as a single partitioning application,such as, a hypervisor.

Control starts at block 300, where the administrative application 126 onthe administrative console 106 processes data on CPU requirements,memory requirements, host bus adapter requirements, etc., for virtualmachines in the nodes 108, 110. In certain embodiments, such data on CPUrequirements, memory requirements, host bus requirements, etc., may beentered by configuration files created by a user on the administrativeconsole 106 or entered directly by the user.

Based on the data on CPU requirements, memory requirements, host busrequirements, etc., the partitioning applications 116, 122 define (atblock 302) the plurality of virtual machines 114 a . . . 114 n, 120 a .. . 120 n for the nodes 108, 110. For example, the partitioningapplication 116 may define the plurality of virtual machines 114 a . . .114 n for the node 108 and the partitioning application 122 may definethe plurality of virtual machines 120 a . . . 120 n for the node 110.

The partitioning applications 116, 122 associate (at block 304) a poolnumber with the virtual machines in a node. For example, thepartitioning application 116 may associate pool numbers that numericallyrange from 1 to n, for virtual machines 114 a . . . 114 n in node 108.The partitioning application 122 may associate the same pool numbersthat numerically range from 1 to n, for virtual machines 120 a . . . 120n in node 110.

The partitioning applications 116, 122 assign (at block 306) virtualmachines with the same pool number in either nodes 108, 110 to bepartner virtual machines. For example, if pool number one has beenassociated with virtual machines 114 a and 120 a, then virtual machines114 a and 120 a are assigned to be partner virtual machines, such aspartner virtual machines 200 a.

Therefore, the logic of FIG. 3 illustrates how the partitioningapplications 116, 122 in association with the administrative applicationcreate partner virtual machines 200 a . . . 200 n within the ESS unit100.

FIG. 4 illustrates logic for initial program load (IPL) of partnervirtual machines 200 a . . . 200 n, in accordance with certain describedimplementations of the invention. In certain embodiments, the logic forinitial program load may be implemented in the partitioning applications116, 122.

Control starts at block 400, where the partitioning applications 116,122 start the IPL for a virtual machine, such as, virtual machine 114 a. . . 114 n, 120 a . . . 120 n. The partitioning applications 116, 122provide (at block 402) the identification and destination of the partnervirtual machine to the virtual machine that is undergoing IPL. Forexample, if the virtual machine 114 a is undergoing IPL, then theidentification and destination of the partner virtual machine 120 a isprovided to the virtual machines 114 a.

The partitioning applications 116, 122 determine (at block 404) if IPLis to be performed for anymore virtual machines. If not, thepartitioning applications 116, 122 present (at block 406) commonresources, such as shared adapters including host bus adapters 104 a . .. 104 m, to the virtual machines in partnership and the process for IPLstops (at block 408). For example, in certain embodiments, thepartitioning applications 116, 122 may present the host bus adapter 104a to be shared between the virtual machines 114 a and 120 a, and thehost bus adapter 104 b to be shared between the virtual machines 114 band 120 b.

If the partitioning applications 116, 122 determine (at block 404) thatIPL has to be performed for more virtual machines, then control returnsto block 400 where the partitioning applications 116, 122 initiate IPLfor additional virtual machines.

Therefore, the logic of FIG. 4 illustrates how the partitioningapplications 116, 122 during IPL present common resources to all virtualmachines in partnership. For example, the virtual machines 114 a, 114 bmay be presented with common resources, such as, host bus adapter 104 a,to communicate to the host 102.

FIG. 5 illustrates logic for providing security for memory access inpartner virtual machines 200 a . . . 200 n, in accordance with certaindescribed implementations of the invention. In certain embodiments, thelogic for providing security for memory access may be implemented in thepartitioning applications 116, 122.

Control starts at block 500, where a virtual machine that may bereferred to as a requester virtual machine, requests memory access fromanother virtual machine. For example, requester virtual machines 114 amay request memory access from virtual machine 120 a. The partitioningapplications 116, 122 determine (at block 502) if the another virtualmachine whose memory access is requested is a partner virtual machine ofthe requester virtual machine. If so, then the partitioning applications116, 122 allow (at block 504) memory access of the another virtualmachine to the requester virtual machine. For example, if the requestervirtual machine is 114 a requests memory access from the partner virtualmachine 120 a the memory access is allowed.

If the partitioning applications 116, 122 determine (at block 502) thatthe another virtual machine whose memory access is requested is not apartner virtual machine of the requester virtual machine then thepartitioning applications 116, 122 does not allow the memory access andreturns (at block 506) an error.

Therefore, FIG. 5 illustrates how the partitioning applications 116, 122allow memory access requests between virtual machines that are partnersof each other. In certain alternative embodiments, only certain memoryaccesses may be allowed even between virtual machines that are partners.

FIG. 6 illustrates logic for providing security for reinitializingprogram load in partner virtual machine 200 a . . . 200 n, in accordancewith certain described implementations of the invention. In certainembodiments, the logic for providing security for reinitializing programload in partner virtual machines may be implemented in the partitioningapplications 116, 122.

Control starts at block 600, where a virtual machine that may bereferred to as a requester virtual machine, generates a request forreinitializing program load for another virtual machine. For example,requester virtual machine 114 a may request a reinitialized program loadfor virtual machine 120 a. The partitioning applications 116, 122determine (at block 602) if the another virtual machine whosereinitialized program load is requested is a partner virtual machine ofthe requester virtual machine. If so, then the partitioning applications116, 122 allow (at block 604) the reinitialized program load of theanother virtual machine to be controlled from the requester virtualmachine. For example, if the requester virtual machine 114 a requestsreinitialized program load for the partner virtual machine 120 a, thenthe reinitialized program load is allowed.

If the partitioning applications 116, 122 determine (at block 602) thatthe another virtual machine whose reinitialized program load isrequested is not a partner virtual machine of the requester virtualmachine then the partitioning applications 116, 122 do not allow thereinitialized program load and return (at block 606) an error.

Therefore, FIG. 6 illustrates how the partitioning applications 116, 122allow a reinitialized program load between virtual machines that arepartners of each other. In certain alternative embodiments, a shutdownrequest of another virtual machine from a requester virtual machineoperates in a similar manner.

FIG. 7 illustrates logic for processing reads, writes, and failures inpartner virtual machines 200 a . . . 200 n, in accordance with certaindescribed implementations of the invention. In certain embodiments, thelogic for providing the processing of reads, writes, and failures inpartner virtual machines 200 a . . . 200 n may be implemented in thepartitioning applications 116, 122.

Control starts at block 700, where the partitioning applications 116,122 receive a notification of an event. The partitioning applications116, 122 determine (at block 702) the type of the received eventnotification.

If the determined event is a write request, then the partitioningapplications 116, 122 write (at block 704) data corresponding to thewrite request to a virtual machine and a partner of the virtual machine.For example, in response to a write request the partitioningapplications 116, 122 may write data corresponding to the write requestto virtual machines 114 a and 120 a that are partner virtual machines.

If the determined event is a read request, then the partitioningapplications 116, 122 read (at block 706) data corresponding to the readrequest from the primary virtual machine of the partner virtualmachines. For example, if virtual machine 114 a is designated as aprimary virtual machine and the data in storage of virtual machine 114 ais mirrored in secondary virtual machine 120 a, then the partitioningapplications 116, 122 read data corresponding to the read request fromthe virtual machine 114 a.

If the determined event is a failure event of a primary virtual machine,then the partitioning applications 116, 122 cause (at block 708) thepartner of the failed primary virtual machine to take over the task ofsatisfying requests from the host 102. In certain embodiments, the nodes108, 110 and the virtual machines except for failed virtual machine keep(at block 710) operating.

Therefore, FIG. 7 illustrates how the partitioning applications 116, 122handle read operations, write operations, and failures of a virtualmachine. In certain embodiments, in the event of a failure of a virtualmachine, the node that includes the failed virtual machine does notcease to operate.

The implementations create a plurality of logical processing units,i.e., virtual machines, from a plurality of processing nodes. A pair oflogical processing units form a redundant system, where if a logicalprocessing unit is unavailable, the other logical processing unit may beused to substitute the unavailable logical processing unit. In certainembodiments, the processing node that includes the unavailable logicalprocessing unit continues to operate. Therefore, the unavailability of alogical processing unit does not lead to shutdown of a processing node.Furthermore, logical processing units that are partners appear identicalto the host. So the failure of one logical processing unit may not beapparent to the host, as the system may keep on functioning with thepartner logical processing unit assuming the functions of the failedlogical processing unit.

ADDITIONAL IMPLEMENTATION DETAILS

The described techniques may be implemented as a method, apparatus orarticle of manufacture using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. The term “article of manufacture” as used herein refers to codeor logic implemented in hardware logic (e.g., an integrated circuitchip, Programmable Gate Array (PGA), Application Specific IntegratedCircuit (ASIC), etc.) or a computer readable medium (e.g., magneticstorage medium, such as hard disk drives, floppy disks, tape), opticalstorage (e.g., CD-ROMs, optical disks, etc.), volatile and non-volatilememory devices (e.g., EEPROMs, ROMs, PROMs, RAMs, DRAMs, SRAMs,firmware, programmable logic, etc.). Code in the computer readablemedium is accessed and executed by a processor. The code in whichimplementations are made may further be accessible through atransmission media or from a file server over a network. In such cases,the article of manufacture in which the code is implemented may comprisea transmission media, such as a network transmission line, wirelesstransmission media, signals propagating through space, radio waves,infrared signals, etc. Of course, those skilled in the art willrecognize that many modifications may be made to this configurationwithout departing from the scope of the implementations, and that thearticle of manufacture may comprise any information bearing medium knownin the art.

FIG. 8 illustrates a block diagram of a computer architecture in whichcertain aspects of the invention are implemented. FIG. 8 illustrates oneimplementation of the host 102, the administrative console 106, and thenodes 108, 110. The host 102, the administrative console 106, and thenodes 108, 110 may implement a computer architecture 800 having aprocessor 802, a memory 804 (e.g., a volatile memory device), andstorage 806 (e.g., a non-volatile storage, magnetic disk drives, opticaldisk drives, tape drives, etc.). The storage 806 may comprise aninternal storage device, an attached storage device or a networkaccessible storage device. Programs in the storage 806 may be loadedinto the memory 804 and executed by the processor 802 in a manner knownin the art. The architecture may further include a network card 808 toenable communication with a network. The architecture may also includeat least one input 810, such as a keyboard, a touchscreen, a pen,voice-activated input, etc., and at least one output 812, such as adisplay device, a speaker, a printer, etc.

The logic of FIGS. 3, 4, 5, 6 and 7 describe specific operationsoccurring in a particular order. Further, the operations may beperformed in parallel as well as sequentially. In alternativeimplementations, certain of the logic operations may be performed in adifferent order, modified or removed and still implement implementationsof the present invention. Morever, steps may be added to the abovedescribed logic and still conform to the implementations. Yet furthersteps may be performed by a single process or distributed processes.

Many of the software and hardware components have been described inseparate modules for purposes of illustration. Such components may beintegrated into a fewer number of components or divided into a largernumber of components. Additionally, certain operations described asperformed by a specific component may be performed by other components.

Therefore, the foregoing description of the implementations has beenpresented for the purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formdisclosed. Many modifications and variations are possible in light ofthe above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. The above specification, examples and data provide acomplete description of the manufacture and use of the composition ofthe invention. Since many implementations of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims hereinafter appended.

1. A method, comprising: partitioning a plurality of processing nodes ina storage system into a plurality of logical processing units, whereinthe plurality of logical processing units can respond to I/O requestsfrom a host coupled to the storage system; grouping at least two logicalprocessing units, wherein data in a first storage coupled to a firstlogical processing unit of the least two logical processing units ismirrored by data in a second storage coupled to the second logicalprocessing unit of the at least two logical processing units; and inresponse to a failure of the first logical processing unit, respondingto an I/O request from the host via the second logical processing unit.2. The method of claim 1, wherein the storage system has at least twoprocessing nodes, wherein the plurality of logical processing units aredistributed across the at least two processing nodes, wherein oneprocessing node includes a plurality of central processing units, andwherein in the event of the failure of the first logical processingunit, the plurality of processing nodes stay operational.
 3. The methodof claim 1, wherein an administrative console is coupled to theplurality of processing nodes of the storage system, further comprising:prior to partitioning, processing, at the administrative console,information on processing requirements, memory requirements and host busadapter requirements for the plurality of logical processing units. 4.The method of claim 1, wherein one or more partitioning applications arecoupled to the plurality of logical processing units, furthercomprising: in response to grouping the at least two logical processingunits, starting initial program load of the first logical processingunit; determining via the one or more partitioning applications anidentification of the second logical processing unit grouped with thefirst logical processed unit; and presenting, by the one or morepartitioning applications, common resources to the first and secondlogical processing units.
 5. The method of claim 1, further comprising:receiving from the first logical processing unit, a request for memoryaccess of a logical processing unit; determining, by one or morepartitioning applications coupled to the plurality of logical processingunits, whether the logical processing unit is grouped with the firstlogical processing unit; if the logical processing unit is grouped withthe first logical processing unit, then allowing the memory access ofthe logical processing unit to the first logical processing unit; and ifthe logical processing unit is not grouped with the first logicalprocessing unit, then preventing the memory access of the logicalprocessing unit to the first logical processing unit.
 6. The method ofclaim 1, further comprising: receiving a write request from the host tothe plurality of processing nodes in the storage system; and writing, byone or more partitioning applications, data corresponding to the writerequest to the first storage coupled to the first logical processingunit and the second storage coupled to the second logical processingunit.
 7. The method of claim 1, further comprising: receiving a readrequest from the host to the plurality of processing nodes in thestorage system; and reading, by one or more partitioning applications,data corresponding to the read request from the first storage coupled tothe first logical processing unit.
 8. The method of claim 1, wherein thepartitioning and grouping are performed by one or more partitioningapplications coupled to the plurality of processing nodes, wherein theone or more partitioning applications comprise a hypervisor applicationof a redundant system.
 9. A system, comprising: a storage system; aplurality of processing nodes in the storage system; means forpartitioning the plurality of processing nodes in the storage systeminto a plurality of logical processing units, wherein the plurality oflogical processing units can respond to I/O requests from a host coupledto the storage system; means for grouping at least two logicalprocessing units, wherein data in a first storage coupled to a firstlogical processing unit of the least two logical processing units ismirrored by data in a second storage coupled to the second logicalprocessing unit of the at least two logical processing units; and meansfor responding to an IFO request from the host via the second logicalprocessing unit in response to a failure of the first logical processingunit.
 10. The system of claim 9, wherein the storage system has at leasttwo processing nodes, wherein the plurality of logical processing unitsare distributed across the at least two processing nodes, wherein oneprocessing node includes a plurality of central processing units, andwherein in the event of the failure of the first logical processingunit, the plurality of processing nodes stay operational.
 11. The systemof claim 9, further comprising: an administrative console coupled to theplurality of processing nodes of the storage system; and means forprocessing, at the administrative console, information on processingrequirements, memory requirements and host bus adapter requirements forthe plurality of logical processing units.
 12. The system of claim 9,further comprising: one or more partitioning applications coupled to theplurality of logical processing units; means for starting initialprogram load of the first logical processing unit, in response togrouping the at least two logical processing units; means fordetermining via the one or more partitioning applications anidentification of the second logical processing unit grouped with thefirst logical processed unit; and means for presenting, by the one ormore partitioning applications, common resources to the first and secondlogical processing units.
 13. The system of claim 9, further comprising:means for receiving from the first logical processing unit, a requestfor memory access of a logical processing unit; means for determining,by one or more partitioning applications coupled to the plurality oflogical processing units, whether the logical processing unit is groupedwith the first logical processing unit; means for allowing the memoryaccess of the logical processing unit to the first logical processingunit if the logical processing unit is grouped with the first logicalprocessing unit; and means for preventing the memory access of thelogical processing unit to the first logical processing unit if thelogical processing unit is not grouped with the first logical processingunit.
 14. The system of claim 9, further comprising: means for receivinga write request from the host to the plurality of processing nodes inthe storage system; and means for writing, by one or more partitioningapplications, data corresponding to the write request to the firststorage coupled to the first logical processing unit and the secondstorage coupled to the second logical processing unit.
 15. The system ofclaim 9, further comprising: means for receiving a read request from thehost to the plurality of processing nodes in the storage system; andmeans for reading, by one or more partitioning applications, datacorresponding to the read request from the first storage coupled to thefirst logical processing unit.
 16. The system of claim 9, wherein thepartitioning and grouping are performed by one or more partitioningapplications coupled to the plurality of processing nodes, wherein theone or more partitioning applications comprise a hypervisor applicationof a redundant system.
 17. A computer readable storage medium includingcode, wherein the code when executed by a processor causes operations,the operations comprising: partitioning a plurality of processing nodesin a storage system into a plurality of logical processing units,wherein the plurality of logical processing units can respond to I/Orequests from a host coupled to the storage system; grouping at leasttwo logical processing units, wherein data in a first storage coupled toa first logical processing unit of the least two logical processingunits is mirrored by data in a second storage coupled to the secondlogical processing unit of the at least two logical processing units;and in response to a failure of the first logical processing unit,responding to an I/O request from the host via the second logicalprocessing unit.
 18. The computer readable storage medium of claim 17,wherein the storage system has at least two processing nodes, whereinthe plurality of logical processing units are distributed across the atleast two processing nodes, wherein one processing node includes aplurality of central processing units, and wherein in the event of thefailure of the first logical processing unit, the plurality ofprocessing nodes stay operational.
 19. The computer readable storagemedium of claim 17, wherein an administrative console is coupled to theplurality of processing nodes of the storage system, the operationsfurther comprising: prior to partitioning, processing, at theadministrative console, information on processing requirements, memoryrequirements and host bus adapter requirements for the plurality oflogical processing units.
 20. The computer readable storage medium ofclaim 17, wherein one or more partitioning applications are coupled tothe plurality of logical processing units, the operations furthercomprising: in response to grouping the at least two logical processingunits, starting initial program load of the first logical processingunit; determining via the one or more partitioning applications anidentification of the second logical processing unit grouped with thefirst logical processed unit; and presenting, by the one or morepartitioning applications, common resources to the first and secondlogical processing units.
 21. The computer readable storage medium ofclaim 17, the operations further comprising: receiving from the firstlogical processing unit, a request for memory access of a logicalprocessing unit; determining, by one or more partitioning applicationscoupled to the plurality of logical processing units, whether thelogical processing unit is grouped with the first logical processingunit; if the logical processing unit is grouped with the first logicalprocessing unit, then allowing the memory access of the logicalprocessing unit to the first logical processing unit; and if the logicalprocessing unit is not grouped with the first logical processing unit,then preventing the memory access of the logical processing unit to thefirst logical processing unit.
 22. The computer readable storage mediumof claim 17, the operations further comprising: receiving a writerequest from the host to the plurality of processing nodes in thestorage system; and writing, by the one or more partitioningapplications, data corresponding to the write request to the firststorage coupled to the first logical processing unit and the secondstorage coupled to the second logical processing unit.
 23. The computerreadable storage medium of claim 17, the operations further comprising:receiving a read request from the host to the plurality of processingnodes in the storage system; and reading, by one or more partitioningapplications, data corresponding to the read request from the firststorage coupled to the first logical processing unit.
 24. The computerreadable storage medium of claim 17, wherein the partitioning andgrouping are performed by one or more partitioning applications coupledto the plurality of processing nodes, wherein the one or morepartitioning applications comprise a hypervisor application of aredundant system.